Now for the refraction pass. it's pretty much the same thing. select all colors and, on their own layers, fill them with white. remember that reflections go on top of refractions.
Now let's start assigning depth values. starting with the floor. the floor, being so large, needs a gradiation since it has a vast depth. now use the eyedropper once on the depth map where the box and the floor visually "meet". and once on the depth map where the floor is farthest. (see below image) if you do not have a floor or any other reference object, simply approximate.
Now lock the layer's opacity and with the two eye-dropped colors, and the gradient tool, make the gradiation in the direction which is getting further with distance. use the depth map as a guide. the depth inside the refraction and outside shouldn't be too different. this applies to any object large enough that it needs a gradiation, including fog.
Now for the other objects, use the same technique. for example, if the object is visible both outside and inside the reflection/refraction, you can use the eye-dropper on the object in the software-produced depth map
If the object is not seen outside the reflection/refraction, you can use other objects which are relative to the object.
Now turn on all of the objects which were selected and colored in the previous steps and turn off all of the rendered layers except the software-produced depth map. our depth map is now ready.
Go to the top-most layer and select all (select menu > all) and copy merged (edit menu > copy merged). paste what you just copied into a blank alpha channel. now make your diffuse render active on the top-most layer and open the dof filter (filter > blur > lens blur in photoshop cs). in the filter parameters window, select your depth map. if there is only one alpha channel it will select it automatically. otherwise, select it from the drop-down. other filters make you select the depth before going into the filter so here's how. select the contents of the alpha channel by pressing the load channel as selection button on the bottom of the channels tab. enter the filter and bob's your uncle. from here on, you should know what to do. if you don't, refer to your dof filter's documentation.
this solution works but can be quite a hassle you're using it on an animation. so until our great software providers update their software, think... stills.